tonyfazt

did u replace the ecu

deanshark

Seeing how your car is a 97 people are going to get confused b/c the OP's car is 94. (Total different code set-up) It is VERY common for the drivers side coil to go bad when the car gets hot. The heat effects it when the engine gets hot but when it's cold it's fine. That might be why it tested fine when you checked it. Try switching the coils with each other. If it runs fine like that, (after it gets warmed up) then the coil that was on the drivers side is garbage.

compx

Took car in found code for main oxygen sensor right bank (which I knew about). What I didn't know was how some older cars work and rely on these o2's. My nissan will bypass an o2 if it believes it to be faulty where apparently my 94 lexus does not thus causing the car to respond to a constant lean condition by providing fuel.

All said and done, I ordered the following from RockAuto and got my part in 2 days:
1994 LEXUS LS400 4.0L 3967cc V8 MFI (U) [1UZFE] DOHC
DENSO 2344211 (234-4211) Oxygen Sensor $ 56.79 $ 0.00 1 $ 56.79
Shipping First Class Mail $ 2.13
Order Total $ 58.92

Got it on Saturday, installed sensor today and check engine light is gone, no other codes found. Car drives great, has its power back and runs right through the gears smoothly.

Still a few other things to address EGR pipe and gasket. I did manage to find a good condition intake boot for $10 bucks and my local import j/y which I installed as well.

As of now, the car drives great and no further concerns to report.

Thanks for everyones help and good luck to everyone still sorting out their Lexus.

Compx

sonny4649

Hi compx,

I'm new here and posting for the 1st time.

I know it was couple of months ago however, I saw all the help you were getting and you finally found that it was the main oxygen sensor that were giving you the problem.
I'm having the rather same problem w/ my '94 LS 400 but my car doesn't stop idling, just smell gas and no power.
I was wondering if you can help me where the sensor is located and how to change it by showing me either by photos or video?
I'm a beginner, but willing to learn how to fix them with your help and all the good guys on this forum.

Thank you and waiting to hear from you or anyone soon.

sonny4649

cutlass702

Not only is it running like crappy but the a/c wont blow cold the compressor won't kick on. The tranny is starting off in third gear trac turns off and won't come on.no power what so ever.exhaust Smells like rotten eggs. Check engine light on and off. Every thing happened from one momment to the next! The car was running beautifully earlier the same day... I'm very confused I'm being told its the ecu due to all of these problems at once. It is a very well kept ls400 with 111k on the ticker.... please help! Thanks

Lavrishevo

iTrader: (1)

There is a wiring harness in the trunk near the top and by the hinges of the trunk. Check that and make sure it is not frayed or broken. If not, and there are no other obvious signs of then you could pay Lexus to diagnose it and then go get the part and put it in. Obviously, the ECU is going to be cheapest to have it fixed. There are always salvage yards as well. But when it comes to ECU's, you can't return them.

kayuwong

Mine is the same thing, I m 100% sure, it is your ECU capacitor (C831) is blown, don't be lazy to take it out and check. Symptom is stall at startup, run rich on gas, no AC, glowing red exhaust manifold. I rolled my dice and pick up an used on at local junk yard. Plug in and everything is perfect. You can try replacing caps at local TV repair shop if you can't find a ECU replacement. Good luck.

kayuwong

ECU cap (C831) is blown, I can bet 100 bucks on it. Good luck.

cutlass702

THAT'S ABOUT THE BEST ANSWER I'VE HEARD IN THIS WHOLE THREAD.! SIMPLE AND RIGHT TO THE POINT THANKS THE COMPUTER HAS BEEN OUT FOR SOME WEEKS NOW. I DID NOT THInk about a tv repair man being a solution. Great idea as I know a couple places here in ft lauderdale FL. When u say capacitor c831 is it labeled this way the circuit board.? Is this the only problem with these ecu's? What r the specifics on this capacitor so just in case I know what I want. Thank you

kayuwong

I did replace mine with a used ECU, but I opened up my old ECU and spot one blown capacitor (C831) and other capacitor has brown goo coming out (C103) . I did de-solder two capacitors out and spot the bottom cover of the capacitors are leaking. I went ahead and dig through my old computer mother board and found two same value capacitor to solder back on the board. But I have not have time to test it out yet. You can always go higher voltage on capacitors, better protection.

crcuevas

I have almost the same problem. It will not go beyond 1200 rpm. I did replace the knock sensors and that involved in removing the intake manifold. Replace the gaskets and put everything back to together and thats when the problem started. Also had the ECU repaired and same problem. I'm back taking it a part again to see if i missed anything. Now I did noticed that the air intake gaskets had oil residue? is that normal? Should i replace the gaskets again? The motor will not pass 1200 rpms (sounds like it wants to die). But it idles great!!!! and starts with no problems. Any ideas?

Yamae

Oh, those are Nichicon's PF(M) Type. It is natural to fail after the many years of use because the infamous liquid "ammonium chloride" damages the sealing rubber.

Toyota had been in use of this type of infamous capacitors up to UCF20/21. My 98 Celsior has them many in the ECU shown below.


Those who own UCF10,11, 20 and 21 have to be careful for the caps.

cutlass702

So I finally got some money to fix my ecm because I cannot find a cheap used one. After taking it apart I,noticed no Goo like substance . But a greenish film around the prongs under the capacitor and becoming a problem on the board as well. Also the caps u had mentioned, one looks fine but there are a few other ones with that same film on it. C740,c103, c108 , and a little bit on c106.C831 LOOKS OK. I don't have a clear enough camera to take pics.should I send this out to get all these replaced. I'm going to try to find a tv repair shop locally.or ship it out .... What to do?

kayuwong

Yeah it is very difficult to check capacitor while they are solder on the board. I have replaced two bad caps on mine. Tested and confirmed it is working in order. Now I have one extra ECU sitting in my garage. Let me know if you are interesed. I paid an used one for $200 at local junk yard. Luckily it turned out to be working condition. 93-94 ECU is the toughest to find, trust me, I spent several days of calling around and driving around town. PM me if interested. Parts no is 89661-50142.

kayuwong

The abnormal film is sign of leaking already. Good luck. 93-94 is known for bad caps on ECU and dash board cluster. I experienced both of them and got them fix by DIY. LOL Good luck.